Anything But Simple
by BrittFaceNess
Summary: What happens when the only consulting detective in the world, and the 11th Doctor have to solve a case together?
1. Chapter 1

_**a/n:** Hello sweeties! Review & just know I'm not as clever as Sherlock or the Doctor. _

_**Disclaimer:** I don't own Sherlock or the Doctor, sadly enough. The ones who own them do._

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It was midnight in the city of London. The golden glow of the city lights shined, and the honking of cab drivers was a distant familiarity to all the English living there or nearby. Humidity hung in the night air but the December temperature was still cold and frosty. Rain threatened to fall from the clouds above, and soon.

The Thames River was strangely calm despite the slight wind, and up close it seemed as if the water went completely still.

There is a flicker of movement on the surface of the water, as if a brown trout skittered to the top, then hurried back down to the depths. But no, the rippling continued on. It was as if something was trying to escape.

A hand emerges from the water, pale and ghastly-looking. It stretches its fingers out towards the sky, reaching. The index finger twitches slightly. As quick as it came, the hand suddenly falls limp and splashes back into the river water.

Thames River is once again flowing along. And nobody noticed the oxygen bubbles slowly fading away.

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The flat of 221b Baker Street was peaceful at the moment. At least, the most peaceful it could get. They had just solved a four-day case, a string of murders finally sorted out and picked through to the very last detail.

John Watson had the pleasure of waking up that morning to a long, hot shower, a cup of tea, and actually having time to read the newspaper. The problem was, was that Sherlock hadn't slept even a minute last night. He had been in the bloody kitchen doing some kind of experiment that John would rather not know about.

John sipped on his tea leisurely, stealing a glance at Sherlock who was spread out on the sofa. His long legs draping over each other, arms above his head, with his eyes fixated on the ceiling above him. It was a little scary to see Sherlock like this – it meant he was bored. And anyone knew that a bored Sherlock was not good. Not a good thing at all.

"Sherlock?"

Only his mouth muscles moved as he replied with a faint and slightly annoyed. "Hmm?"

"Why don't you…do something? Go to the lab. Annoy Lestrade." John said, folding up the newspaper in his hands and setting it on the small table beside him. "Anything but just sitting there silent."

A small smile curled onto the consulting detectives lips. "I'm thinking, John."

"Exactly." John stood up. He hooked his finger in his cup's handle and sauntered into the kitchen. John really didn't want a case to come up today, at least not until he had fully recovered from the last one. His sleep schedule hadn't quite adjusted to Sherlock's yet – along with his eating habits. He shook his head. That man. Setting the cup in the sink, the army doctor glanced around the kitchen. Nothing looked out of place, nothing different. Jars with random body parts and liquids were set on the counter, the table was cluttered with miscellaneous junk, and the fridge probably still had the same objects in it. Sherlock must have just been playing with his normal toys until the break of dawn.

Returning to the living room, John found Sherlock in the same place. John glanced around the flat, and then gave a small sigh. "Well I'm going out."

"Out? To where?" Sherlock murmured curiously.

"Grocery shopping, perhaps."

"Perhaps, yes."

What in the world was that supposed to mean? A split second of silence, then John regained his thoughts and took his coat off of the rack. "Please don't blow the place up while I'm gone. Or shoot the walls. Or flood the kitchen." The list could go on forever. It was like telling a three-year old not to touch the shiny objects right before his eyes.

Before John could get out the door though, Sherlock's phone buzzed, signaling a text. They both knew what that meant. He looked over his shoulder as Sherlock studied the screen of his phone, brows furrowed. It was obviously Lestrade.

"Well?" John asked. Sherlock stood up, stuffing his cellphone into the pocket of his pants. He stepped up on the coffee table, then back onto the floor and grabbed the newspaper John had just been 'reading'.

"John?" Sherlock said. "Did you see anything unusual in here? A murder, a drowning, any-" he went silent, and then threw the paper carelessly over his shoulder. "Of course it wouldn't be in the paper. That means Lestrade just found out about the girl."

"Sherlock you're muttering to yourself again." John commented. But he went on mumbling.

"Which means it's more serious than just a drowning, perhaps. Maybe it was a murder. Or maybe the girl committed suicide." John watched as Sherlock slipped his elegant arms into the sleeves of his coat, picking up his scarf. Now he looked at John and smiled. "Grocery shopping can wait, John. We have a case."

John sighed. "Obviously."


	2. Chapter 2

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"So where are we off to now, Doctor?" Amy Pond asked, walking around the circular control panel of the Tardis, running her slender, pale fingers on the railing beside her as she did. Her deep, brown eyes followed the Doctor's hands as they skillfully punched buttons, pulled levers, and turned various knobs. The Tardis made a clunking noise, some whirs, and then with a jerk they were off.

The Eleventh Doctor's eyes met Amy's and he smiled. "It's a planet that is very familiar and probably very boring to you." The smile he wore quirked into an apologetic one "Sorry, Pond."

Amy crossed the distance between them, her arms folded over her chest. She raised one perfect eyebrow. "I'm sorry, Doctor. But you have to know that no matter what planet we're on or what time period; it's _never_ boring with you alongside."

Amy watched as a grin spread across his face. "Well…yeah." He admitted sheepishly. It could have gone as either an insult, or a compliment, but he obviously took it as the latter.

Eleven spun around gracefully, arms flailing causing his tan tweed jacket to whirl around him. He punched another button. "I received a message earlier."

"A message? Like…a message for help?" Amy asked curiously, watching him.

"Hmm…that's the difficult part, you see. The message had no message." The Doctor mumbled.

A message that held no message?

"Doctor…"

From the front pocket of his jacket, he withdrew a small object. Amy stepped closer and recognized it as a-

"Is that a fish scale?" she wrinkled her nose in dissatisfaction. It was a light blue, and when the Doctor turned it a fraction of an inch, it glinted green. "That's it?"

Eleven looked mortified. "Pond, this is _not_ just any old fish scale." He peered at the scale. "This fish scale is from one of the oldest type of fish species in the entire universe."

The redhead blinked, her fingers touching the scale. Indeed, it did not look like an ordinary fish scale you would find swimming in a lake. Amy wasn't an expert on fish, but she DID know that they didn't have any that looked like this. At least, not _Earth_ fish. And not any she had seen.

"What planet did this come from?" she asked him, voicing her thoughts.

The Doctor looked excited all of a sudden, his features vibrant. "Earth."

Amy smiled a little. "Of course you want to find out where it came from and why it was on Earth."

"Of course, Pond." He tucked it carefully back in his pocket.

The Tardis sputtered and whizzed like usual, and with one last shake, everything stilled. They had landed.

Amy practically skipped to the door, opening it wide. Momentarily confused, she knew they were on Earth, but didn't know quite where. The sky above was filled with rain clouds and all around taxis and pedestrians went by.

"London." The Doctor stated as he joined her outside, the Tardis door closing behind him. "United Kingdom. To be precise, we are somewhere between Southwark Bridge and Waterloo. At least the Tardis will blend in completely."

"Ah, I see." She saw a river nearby as they started walking.

"Thames River." Eleven said as they reached the banks. Rocks and rubble crunched under their shoes as they walked. "I scanned the fish scale and it had traces of water on it. This water, to be exact."

Amy gave a nod. She looked ahead and saw people gathered by the edge of the water. Not mundane people, she noticed. Some were in uniforms, others just in black or normal clothing. A couple squad cars were parked a bit away. "Doctor?" but he had already noticed.

A body lay on the ground, covered mostly in a white sheet. As the two of them drew closer, Amy realized it was a naked girl with black matted hair, pale skin tinted slightly blue. Her feet were only inches from the river water. Had she drowned?

A man was hovering over her, touching her hair, rubbing his fingers together, pressing them to her neck. He wore a long, black coat with a dark blue scarf wrapped around his neck. Hearing their approach, the man looked up, his pale green eyes assessing them carefully. "And who are you?"

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><p><strong><em>an:_** _review please! :) _


	3. Chapter 3

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John Watson watched with a deep interest as the man and girl came striding up to the crime scene. People usually didn't do that. They mostly didn't know what was going on, or stayed away because they saw the squad cars and men in blue suits all around the area. But no, instead these two just walked up like they were part of the team. A quick glance at Lestrade told him that wasn't true – he looked confused and sort of impatient.

At that moment, the consulting detective who had been studying the dead girl's body with fascination glanced up at the man. "And who exactly are you?" he said not-so-politely. John guessed it was because they had just interrupted a very important moment of his concentration.

John pulled his gaze away from Sherlock and it landed on the man. He wore a brown suit, with a distracting bowtie the color of crimson. His soft, brown hair was pulled over to the right side of his head, and a smile was plastered on his face making him look like a nine-year old boy in a candy shop.

"I'm the Doctor." He replied cheerfully, and then pointed a finger at the redhead beside him. "And this is Amy Pond."

If that meant anything to any of them, John didn't see it. Lestrade put his hands on his hips. "This is a crime scene. It's off limits right now. You can come back later when we're finished."

"Oh! Right, sorry." He took out what looked like a badge and flashed it in the policeman's face. "Here you are."

Lestrade studied the badge carefully, brows pulled together. "You're a high-ranking detective? But…no one sent for you!"

John's eyes flickered to Sherlock's and they locked gazes. Who was this man exactly? Sherlock looked back at the Doctor and began to study him carefully.

The Doctor (as he called himself) knelt down beside the girl's body and took out an object from his coat pocket. It looked like…well, John didn't quite know what to compare it to. It was sort of like a probe. "Mind if I take a look?" he asked, nodding in the direction of the girl.

Lestrade could do nothing but watch as he allowed the mysterious doctor to do whatever he liked. After a couple moments, the cop shook his head as if he couldn't deal with a situation as weird as this. He walked off towards where his other men were talking.

The redhead (Amy, was it?) took her place next to the Doctor. "Well? Is it the source?" she asked.

The Doctor smiled up at her enthusiastically. "Yep." He pushed himself up off the ground with his lanky legs, stuffing the probe object back into his coat pocket.

Sherlock's eyes narrowed. "What source? Who is this girl?"

"Well," he scratched his cheek, speaking slowly. "She's not from Earth."

"Excuse me?" John retorted. Sherlock stayed silent, looking slightly offended and also a bit repulsed. This man must be a whacko.

"Oh, there's also another thing."

"What is it?"

A gasp filled the chilly air, and four pairs of eyes snapped to the girl lying on the rocks. Another gasp for oxygen, then a pale hand came up and ripped the sheet off. The girl's big, golden eyes stared up at the grey sky.

John's mouth fell open in shock. The girl had just been _dead_. Dead as dead could be. He had felt for a pulse, clutching at her wrist and pressing his fingers to her neck. John had actually been hoping the poor girl was alive or at least in a coma – but no, all the signs pointed to her death.

And now she was alive and breathing, her eyes searching them all with fear and confusion.

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><p><strong><em>AN: _**_hello sweeties! sorry it was such a short chapter, with it being Christmas and all I couldn't quite concentrate..._

_so anyways!_

_Review! :) _


	4. Chapter 4

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The Doctor was used to trying to explain odd situations to the humans of this planet called Earth, but sometimes it amazed him at how long it took them to piece the clues together. A supposedly dead girl who came back to life – obviously it meant she was from another planet. It was impossible for humans to regenerate themselves or breathe the breath of life once they were deceased. Yes, there were miracles at times but the Doctor doubted they always used that excuse. Did they? Or did they ever think that maybe, just maybe, it wasn't a miracle. Maybe the so-called "human" was not actually one? Maybe it was an alien? Of course they wouldn't think that, the Doctor thought to himself. Humans like to attach themselves emotionally to superstitions and such. Not that there was anything wrong with that – of course not. It just sometimes…well, got in the way. But the Doctor (always being as good-hearted as he was) always tried to sort things out in the little minds of the humans.

He looked sideways at his companion next to him, and saw that her eyes were already locked on his – waiting for his next move, waiting for what he would say next. The side of her mouth tugged upwards, causing him to do the same.

The Doctor swiveled back around in the direction of the girl and walked over to her cautiously. "Are you okay?"

The girl clutched the sheet around her thin body, her black stringy hair draping around her bare shoulders, and dark brown eyes full of fear. Well, that answered his question. She was obviously not alright – and the two men beside him were probably not helping the case. They stared and oogled like she was a new exotic animal in a zoo. The Doctor held out his hand. "I'll take you home." He said softly, keeping his eyes locked with hers the whole time.

"Home?" one of the men repeated, stepping forward. "Where exactly would 'home' be? You can't just take off with her, _Doctor_."

The Doctor gave the tall, dark-haired man a patient look, smiling a little. "Actually I can. She doesn't belong here."

The man looked annoyed that he hadn't answered the first question, so he probably felt the need to repeat it. "Where is 'home'?"

"I don't know."

"You don't…you don't know?"

The Doctor turned his attention back to the girl, hand still held out kindly. "Come now, dear. Let's get you out of this cold weather." After a couple of hesitant seconds, she took his hand and let him help her up onto her feet – quite unsteadily, the Doctor noted. They would have to get to the Tardis quickly, before the poor thing froze to death.

Amy came to his side, slipping an arm gently around the girl's waist. "This way." The two of them started to hobble off at a slow pace towards the Tardis.

"Listen, this is MY case!"

The Doctor turned and smiled broadly at the dark-haired man in a trench coat. He looked so interesting – like he was breaking down every movement, every detail. Maybe he could help. Maybe this man could be useful. "Yes, of course it's your case. Would you like to tag along?"

The other man (the one in the jumper) interrupted. "Exactly where are we tagging along to?"

The Doctor's smile stayed in perfect place as he eyed the two men. "Wherever you feel like."

He turned on his heel and followed his Amy Pond back to the Tardis.

"Sherlock, you can't be ser-"

"Of course I'm serious, John. Why wouldn't I be? I'm always serious, surely you should know that by now. This is my case, John. Mine. It's a very interesting case, also. I can't just give up an opportunity like this. Do you WANT me bored at home? Of course not. So let's go."

Before John could protest, the consulting detective was following after the man in the brown suit. Well, what else could he do but to follow? Isn't that what he always did? Isn't that what it always ended up as? Him trailing after Sherlock? Of course.

He matched his pace with Sherlock's, and they stayed a couple steps behind the Doctor and the two others.

Lestrade would be mad as hell, John thought briefly. They had just run off with two complete strangers, plus a girl who had been brought back to life.

Brought back to life. That was still tugging on his mind. How could all of this be possible? The man who called himself the "Doctor" had said she came from another planet.

Another planet.

_Another planet._

What had this world come to? What if this man was just a lunatic? But surely he wasn't – Sherlock was interested enough to follow after him. I mean, who wouldn't be curious of a girl like this?

Soon enough, they had gotten onto the roadway and the Doctor stopped in front of a blue telephone box. What was he going to do? Make a call? John watched closely as the redheaded girl opened the door, stepping inside with the girl.

Before either Sherlock or John could say or do anything, the Doctor turned to them. "Now, I love this part – I really do- but since we're kind of on a tight schedule right now with the whole saving-a-girl-from-a-different-alien-race thing I'm just going to throw it right out there. It's bigger on the inside, yes. Now, come along." He disappeared into the telephone box.

John looked at Sherlock and they exchanged a questioning look. John went first, stepping through the door.

And he caught his breath.

It definitely WAS bigger on the inside, that's for sure.

Sherlock came up beside him. "Hm. Makes sense."

John shot him an incredulous look. Did _anything_ surprise Sherlock?


	5. Chapter 5

**_a/n: _**_Sorry it took so long for this blasted chapter to be put up! My mind has been quite preoccupied with the new Sherlock episode (my fellow Sherlockians would understand). _

_Sorry for in advance - it's a short chapter. Please review!_

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The Doctor brushed aside the girl's matted hair, staring into her gorgeous eyes. The shirt and shorts Amy had given her hung loosely on her body, revealing how underweight she truly was. Her skin was slowly regaining its original ivory color, lips a light pink.

"Do you know your name?" The Doctor asked softly.

The girl's eyes flickered to the people behind him, who were obviously watching her with curiosity. They met his again. "Siren."

"Siren. What an interesting name." He murmured mostly to himself. "Do you remember how you got to Earth?"

Siren titled her head a bit to one side, thinking with great thought it seemed. "I'm…not sure. It's all a blur." Her brows came together in frustration.

"But do you remember what planet you're from?"

"Pisci." Siren responded, her stare once again latching onto the Doctor's.

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John stood beside the consulting detective, inside the telephone box that was bigger on the inside, and watched the scene unfold before him with great interest. They had so far found out what the girl's name was and what planet she resided from.

"Pisci." John heard the Doctor repeat. He felt tension in the air, thick enough to cut. From what John could gather – this said-planet was bad news.

The Doctor was silent for a whole minute before standing up straight and walking over to them. His eyes met John's, then Sherlock's. "Let me warn you-"

"No need," Sherlock interrupted, "It's fairly obvious, _Doctor_."

John smiled at his shoes. He had fully expected for Sherlock to deduce every detail that was happening.

Sherlock continued on. "The girl's name is Siren – it's the Latin word for 'a partly female creature whose singing lured sailors and others to their deaths'. A mermaid, if you will. And then the planet – Pisci. It's clear that _pisci_ is the word for 'fish'. A half-fish girl, coming from the planet of fish." The corner of his mouth tipped into a smile. "Now for the fun part. The part that you were to warn us about. The part that caused you to be dead silent for precisely fifty-eight seconds."

John looked at him, waiting for more. This man always seemed to amaze him at every turn.

"The planet," Sherlock stated simply, "Is a planet made up of mostly water, probably very little land. The mermaid species that reside there were curious of the land. They wanted to, perhaps, explore the land. But, ah. They couldn't, could they? No legs, only fish tails. So what did they do? They - "

"Enough!"

Silence loomed over all of them. John looked up quickly and saw the Doctor, eyes blazing and mouth set in a thin line. It looked like an odd expression on the usual kid-like man. Sherlock, however, was smiling. "This is quite fun, isn't it?"

The Doctor set his jaw. "This is _anything_ but fun. This girl's life is at stake here, don't you realize that?"

In response, Sherlock's eyes shifted to Siren, then back. He looked unconcerned.

John cleared his throat loudly. "Well then…should we get going then? To this planet?"

The Doctor twirled around, striding quickly to what looked like a control panel in the center of the room. John turned to Sherlock. "Sherlock, what's happening?" He said in a soft whisper.

Sherlock avoided his gaze for a couple seconds, and then looked straight at him. "The species of the planet, remember what I said?" He waited for John to nod. "They were experimenting on their own kind – trying to find a way to transform themselves into full human beings. Some went wrong."

John thought for a bit, and then slowly pieced the parts together by himself. The experiments went wrong, so they had to dispose of the bodies. That being said – they sent them off into space and they somehow ended up on Earth.

John's horrified gaze met Sherlock's. What had they gotten themselves into?

No, he corrected himself, what had _Sherlock_ gotten them into?


	6. Chapter 6

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It was a very awkward situation at the moment. If you would, imagine being tossed around on a ship – thrown into people you barely met and stumbling on your flat mate's toes. But that wasn't exactly where the awkward feelings came from. At the moment, it seemed, John's back was to the wall of the Tardis. His flat mate, his friend, the only consulting detective in the world – had been propelled from beside John, to practically flattening the other against the wall.

Sherlock straightened and fixed his coat. John cleared his throat. They avoid each other's eyes.

"You're departure and landing needs some mending, don't you think?" Sherlock retorted.

The Doctor and Amy had been casually holding onto the railings around the control panel, knees bracing the movement all the while they had been traveling through time and space. Obviously they were used to it.

"Yes, well…" the Doctor mumbled mostly to himself, giving a roll of his eyes. "It takes practice."

Amy gave a small laugh, giving the Doctor a secret smile. "Yes, of course. Since you haven't had a lot of time to do that by now."

In return, the Doctor stuck his tongue out childishly at her. "Be quiet, Pond."

Sherlock cleared his throat loudly, reminding the Doctor and Amy what they were doing in the first place. They seemed so at ease, those two, even though what was going on. John marveled at how they could do that.

Amy skipped down the couple of steps and over to John and the detective. "We've decided to leave the girl here for now. She's not in a good state to be walking around. I've put her in a room to rest."

John nodded immediately, understanding this from a doctor's point of view. "Excellent point. Erm…so did we just land on the planet…Pisci, was it called?" He stole a quick glance at Sherlock, who was staring at the ceiling with a look of disbelief on his face. John could just hear the thoughts stabbing in John's direction: _"John, please pay more attention." – "John, were you listening at all?" – "John, follow along. It's not that hard." _

However, all Sherlock said was, "Yes. We've arrived."

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Amy Pond was intrigued by the two men tagging along with her and the Doctor. The one – John, was his name - was adorable in an odd way. He had a habit of smiling awkwardly and clearing his throat when nervous. On the other hand, the other man – Sherlock – was quite the opposite. She wondered how the two ever could stay near each other for short periods of time.

She opened the door of the Tardis and cold air rushed in, blowing her flaming red hair back gently behind her shoulders. Exiting, Amy was followed by the three men.

Their surroundings were definitely not what she expected. Amy had envisioned a warm beach, crowded with palm trees and a jungle maybe, and the water blue and clear. But instead, the warm beach was cold, wet sand. Most of the land as far as she could tell was covered with large rocks and caves. The water is what disturbed her most though. It-

"The water is black. Why?" John asked curiously, stepping towards it. Sherlock however, grabbed his arm before he could get close to it. They both peered at the dark ocean.

Eleven came up beside Amy, crossing his arms as if to fend off the chilly air. "It's a strange planet. Lots of myster-"

"Barely any sunlight combined with the type of sediment and the creatures living in the water effect the color of it. Also the temperature of the water is extremely cold. Usually in warm water the sand is able to sink to the bottom and settle there – which is why places such as Florida and the Caribbean islands have such clear water." Sherlock said, turning up the collar on his coat.

Amy stared at him, her mouth a little open. He was brilliant and amazing – that was for sure. Her eyes flickered to John, who was smiling at the sand by his feet, and then to her raggedy Doctor. He had his lips pursed a little, as if offended. Silence fell between all of them for what seemed like hours.

John cleared his throat loudly. "So..erm…Doctor?" He asked a little awkwardly. "Are we going in the water? What are you planning to do?"

The Doctor snapped out of his reverie and a smile formed on his lips. "Plan. Of course I have a plan." He said with a wave of his arms. "I always have a plan. Plans are certainly in my category of expertise. Isn't that right, Pond?"

Amy gave a single laugh. "Yes, yes." She knew it wasn't true – but there was no point in knocking the Doctor's ego down any more than it had been that day. Her poor, poor Doctor. He was almost always used to being the one knowing every little detail – since he was the one who took her to the planets he knew best, and she knew nothing of.

"I'd like to know what this plan is." Sherlock muttered, raising a brow in question. John sucked in a breath, and Amy held hers. They all stared at the Doctor.

"I hope you all know how to swim." The Doctor simply said, the grin never leaving his face.

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**a/n: Review! Tell me if I should continue or not! Ideas and such are welcomed (: I'll be sure to give you credit! **


	7. Chapter 7

**a/n: Yay for quick updates! **

**First off, thank you for all the lovely reviews. I wouldn't be continuing this unless you guys told me otherwise, so thank you.**

**Second - the Harry Potter fans will spot the magical item I threw in here ;) the mention of this item might actually inspire a new fanfic in the future. Who knows.**

**Enjoy! I really do try not to make cliffhangers, but it's in my blood. **

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None of them knew what exactly was going to happen next – not even the Doctor or Sherlock. Yes, Sherlock probably had eight or nine outcomes forming in that amazing mind of his, but anything could happen.

John wasn't nervous of course – being in Afghanistan had trained him to block out emotions like nervousness or fear. He sat himself down on the sand, taking deep breaths to calm those nerves.

The Doctor had mumbled something earlier about needing to get that one thing in that one place in the Tardis and dragged Amy off with him inside. They had been searching for a couple minutes now. John wondered curiously what he could be trying to find at a time like this.

John heard footsteps coming up from behind and Sherlock stopped beside him, hands shoved deep into the pockets of his coat.

"This is insane, Sherlock." John muttered with a shake of his head.

A smile touched the consulting detective's lips. "It's either this or my boredom."

They both laughed a little together, remembering all the bullet holes in the flat's walls. It was true – John preferred this Sherlock instead of the bored one.

The sound of approaching voices and footsteps snapped them out of the moment. John stood up, brushing the sand from his pants. The Doctor stopped in front of them, smiling big. "I found it!"

"Found what, exactly?" Sherlock asked.

The Doctor held up a clear, plastic bag – similar to the ones you would hold a goldfish in. It was half-way filled with water. Settled on the bottom was a mass of what resembled slimy, green weeds.

John blinked in confusion. "What is it?"

Amy leaned forward, smiling at him. "Gillyweed."

John raised a brow, waiting for more a more detailed explanation. Sherlock did the same, a smirk on his face.

"Gillyweed!" the Doctor said loudly. "A plant that comes from the Mediterranean Sea! When eaten, one can basically sprout gills and webbed limbs!" He gave a little shrug. "Of course, originally it only works for witches or wizards, but I have a connection and he was able to experiment a bit to-"

"Hang on," John interrupted. "Did you just say…_wizard_?"

Amy winced. "Doctor, I told you to leave that part out. It only causes more confusion."

"Sorry…"

John looked up at Sherlock, who had been strangely quiet, the past couple of minutes of this conversation. His eyebrows were knitted together in concentration. "Gillyweed." He said, mulling the word over on his tongue.

Sherlock then gave a curt nod – no doubt shoving down words and statements to go against the logic of the substance in the Doctor's grasp. "How long does it work?"

The Doctor smiled a little. "My source told me it can last up to an hour in fresh water. No idea on the duration of it in salt water though." He started to untie the plastic bag.

"So," Amy threw in, "That means we have to be quick about it. We have enough in the bag to get us wherever we need to go down there," She nodded towards the water, "And enough to get back."

The Doctor handed them each a little round of Gillyweed. It was wrapped up loosely, and disgustingly reminded him of rat tails. He then drained the water out of the bag, tied it back up, and shoved it deep in his pocket.

"Bottoms up!" Eleven said cheerfully, throwing the substance in his mouth. The other three mimicked his actions.

John felt the urge to gag as it slowly slid down his throat. He bent over and gasped for air. It felt as if all the oxygen was being sucked from his lungs – from his whole body, for that matter. The doctor felt the overwhelming dizziness.

"_John!_"

John looked up to find the others diving into the water. Amy and the Doctor must have already been used to it – shoving down that urge to throw up. Sherlock stood on the rocks. He had stripped his heavy coat off, along with his shoes. Thinking it was a good idea; John did the same, and then ran at full speed to the water. He had no idea what was going to happen.

Sherlock hurriedly grabbed John's wrist, and they jumped together.

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_Cold._

That is the first word John could think of at the moment as the water rushed around him, engulfing him in darkness. He found that he had no need to hold his breath – for the Gillyweed was unbelievably working. Touching his fingers softly to his neck, John felt…gills.

John's eyes adjusted to the water's lack of light, and he saw the Doctor already advancing deeper, Amy's fiery red hair following after him. A tug at his wrist brought him back to his senses, and John swam after Sherlock.

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The Doctor did not know how long they had been swimming for, but he guessed it was getting closer to the hour than he would've preferred.

The last time he had been here, the water had been crystal clear and tropical warm. The water people were happy instead of depressing and cold. He momentarily wondered if they would remember him.

Eleven started to recognize some of the land(water?)marks around him, and knew he was getting closer.

It came into view then – the water city. Rocks and coral formed into architecture. It was darker than last time -no doubt. Seaweed and moss clung to most of it, giving it an old and worn out look. But to the Doctor – it was fascinating, beautiful, unique. Like always.

He looked back at the other three, who were staring with wonder.

And then shadows around them suddenly took shape and split apart.

They were surrounded.


	8. Epilogue

__**A/N: First off, I want to apologize how long it took me to write up another chapter. With Reichenbach and my birthday, I've been famished.**

**If you haven't realized already, this is the Epilogue.**

**I've enjoyed writing this, and the next time I write a Sherlock/Doctor Who crossover I hope you'll tag along :) **

**Thank you so much for all of the reviews and favorites. You guys make my day when I get an email notifying me of this.**

**So enjoy!**

**And review! :)**

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><p><strong>...<strong>

**..**

**.**

_They were surrounded._

John couldn't believe this. Actually, he _could_, which was quite pathetic in a way, but never mind that. The four of them were back-to-back at the moment, all of their gazes fixated upon the creatures surrounding them, holding some sort of weaponry.

They were, in fact, amazing in a way. Certainly not like the merpeople John had seen in movies or paintings. No, these beings were different.

John's eyes assessed the closest one to him. The girl's fish tail was approximately twice her body size and covered in deep blue and purple scales. It slowly swayed through the water, sort of mesmerizing. Her skin was milky white, the palest he had ever seen, and her light blonde hair made her seem even paler. With a startled jump, John looked at her eyes and saw they were black. Not dark brown. _Black._

"_Why have you come here?"_

John glanced around and blinked, confused. Where had that thought come from? Or had someone spoken? John's confusion grew when he remembered they were underwater-

His gaze locked onto Sherlock's and he raised a brow, silently questioning him. Sherlock gave him 'that' look, then raised his slender fingers to John's forehead, tapping them against it.

Oh. Right.

First a girl who 'comes back to life', a man with a bigger-on-the-inside time-traveling telephone box, merpeople, a new planet, breathing underwater, and now telepathy.

Of course.

Sherlock gave John a small smile, but his attention snapped back to the merpeople once they started to speak again.

"_Talk? Why would we need to talk to you, Doctor?"_

John glanced to his other side and saw the Doctor staring at one of them – John guessed it had been the one speaking. By the look of the Doctor's facial expression, the ex-army doctor realized he was speaking back to them.

**...**

**..**

**.**

Amy watched curiously. As of late, she had been close to her raggedy man in a way she knew she hadn't been close to anyone else. He was her best friend and she was his companion.

So the worry lines creasing his forehead, and the tight set of his mouth obviously told her something was wrong. She realized after a few seconds of thinking, that Eleven and the merpeople were telepathically speaking to each other.

What got her curious bumped up a few more notches though – was the fact that they weren't letting her or the other two as far as she could tell, in on the conversation. So it obviously meant that it was something private.

How long had it been since they dove underwater? Ten minutes? Twenty? Now she wondered if they would even need the other gillyweed, time was passing by so slowly.

Her thoughts were confirmed when suddenly, the beautiful merpeople suddenly vanished as quickly as they had come. Amy turned to the Doctor then, questioning him with her eyes. He stared at her for a few moments, a sad look overcoming his features. A quick shake of his head along with an upward point of his finger told her that it was time to go.

…

The ex-army doctor pulled himself up out of the dark water with the strength of his arms, falling onto the rocks. He breathed heavily but the tightness in his chest slowly faded, leaving him with his normal breathing pattern. The gills and fins had vanished from the four of them and now they sat on the wet rocks, drenched.

John cleared his throat. "So what happened down there?"

When no reply came, John looked to Sherlock for an explanation, but all he received was a downward cast of his eyes. The consulting detective knew, no doubt. But for once, he wasn't bursting out pompously with his deductions.

"Doctor?" Amy prodded gently, placing a hand on the man's shoulder.

"The people of this planet…are dying." The Doctor dragged a hand down his face. "To put it simply – the experiments and such were to try and create a new race. One that could live on and flourish. Only one experiment was a success, the rest failed."

John pieced together the facts. The only experiment that had lived was the one that was currently sleeping in the Tardis. Without a mate, though, John guessed that their plan wouldn't quite work out to their liking.

A moment of revered silence passed between the four of them before the Doctor stood up. He locked eyes with Sherlock. "Case solved, then, I assume?"

Sherlock gave a curt nod. "Case solved."

**...**

**..**

**.**

John stepped out of the Tardis and was met with the air of London and a welcoming sense of home. The consulting detective followed suit, along with the Doctor and his companion. The dark clouds hanging above the city did no help to their saddened mood and thoughts.

The Doctor held out his hand to Sherlock. "Your insight helped, thank you."

The raven-haired man stared at him for a moment before shaking his hand in return. "It was enjoyable despite the outcome. What will you do with the girl?"

"I'm going to take her wherever she pleases. I'm not sure if she'll want to stay on her own planet – it could be slightly depressing." He smiled sadly.

Sherlock nodded slowly, agreeing.

The Doctor then turned to John, a smile on his lips. "Goodbye, John. I have a feeling this isn't the last we'll see of you."

"What do you mean-"

The Doctor grinned, spinning around to face the Tardis. "Come along, Pond! I know of this wonderful planet right beside…" His words faded as he disappeared into the telephone box.

Amy laughed and shook her head. She smiled at John. "I'm sure we'll see more of each other soon. The Doctor never leaves someone's life, not really." Her eyes flickered to Sherlock, who was walking away down the road. "Keep a close eye on him. I can sense that he depends on you more than you think."

John glanced behind him incredulously. "What, Sherlock does?"

Amy gave him a quick and warm hug. "More than you think." She simply repeated. "Goodbye, John."

And with those last words, Amy skipped through the Tardis doors and they shut behind her with a snap. John watched curiously as the blue telephone box slowly disappeared until nothing was there.

The ex-army doctor caught up to his flat mate and gave a long, dramatic sigh. "If I hear the word 'bored' come out of your mouth over the span of the next few days, I will punch a wall."

"That would be quite entertaining to see, my dear Watson."

John just laughed and shook his head. "Do you think we will really see those two again?" He looked at Sherlock.

"I'm positively sure we will. Now, how are we going to explain this to Lestrade?"

Sherlock smiled as John burst into a fit of giggles.

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><p>...<p>

..

.

And all four of them realized then, truly realized, that their lives were _anything but simple_.


End file.
